Pterosaur tracks from the Upper Cretaceous (Cenomanian) Candeleros Formation of northwestern Patagonia, Argentina: Ichnotaxonomic and palaeoecological perspectives from Gondwana

Abstract

New pterosaur tracks from the Cenomanian Candeleros Formation (Neuquén Basin) have been discovered in the Aguada de Tuco locality, northwestern Patagonia, Argentina. Preserved in medium-grained sandstones originating from alluvial deposits, these tracks include both isolated manus and pes impressions. The manus tracks are tridactyl and display a marked asymmetry, while pes tracks exhibit three digit impressions and a subrectangular to subtriangular shape. The absence of a clearly defined trackway, coupled with the limited preservation quality of the documented pes tracks and distinctions from known pterosaur ichnotaxa, prompted the provisional assignment of these tracks to aff. Pteraichnus isp. They also exhibit a different morphology from previously recorded tracks within the same unit, thus contributing to a greater morphological variability of pterosaur tracks for the Candeleros Formation. Additionally, these tracks are found in association with narrow furrows interpreted as traces left by pterosaur manus and pes claws. Considering the shape and preservation of these tracks and the fragmentary record of pterosaurs from the Neuquén Basin, it is possible to attribute the producers to pterodactyloid pterosaurs. Moreover, the observed variability in manus track size, all sharing a similar morphology, suggests having been produced by individuals of different ages rather than different species of pterodactyloid pterosaurs. This study significantly contributes to our understanding of the pterosaur track record from Gondwana and the Cenomanian worldwide.